Happiness is the deferred fulfillment of a prehistoric wish. That is why wealth brings so little happiness; money is not an infantile wish.

Freud is arguing from a psychoanalytic view that what we experience as “happiness” often comes from the belated satisfaction of very old, deeply rooted wishes—wishes formed early in human development (and, in his speculative language, even in humanity’s “prehistory”). Because money and modern wealth are culturally recent goals rather than primal childhood longings, they do not reliably touch the unconscious sources of gratification. The remark fits Freud’s broader skepticism about the promise that civilization, comfort, or material success can deliver lasting contentment; desire tends to shift, and satisfactions that do not connect with early emotional needs may feel thin or quickly exhausted.